[acm, distrib, ssa].c: Add rejoin_timeout configuration parameter

rejoin_timeout
Specifies start timeout (in sec.) before first rejoin attempt.
Exponential backoff is used to space out join retries.

Signed-off-by: Sasha Kotchubievsky <sashakot@mellanox.com>
Signed-off-by: Hal Rosenstock <hal@mellanox.com>